Telomerization reactions utilizing catalysts composed of certain organometallic complexes and transition metals or their compounds

ABSTRACT

Telomerization reactions utilizing catalyst systems composed of (1) liquid hydrocarbon solutions or mixtures of complexes such as those made from (a) n-butylsodium or n-butylpotassium, with (b) alkyllithiums such as n-butyllithium and (2) transition metals or their compounds such as Raney nickel and nickel acetylacetonate give a polybutadiene having a high cis-1,4 content.

I Umted States Patent 11 1 1111 3,760,025 Merkley 1 1 Sept. 18, 1973[54] TELOMERIZATION REACTIONS 3,324,191 6/1967 Wofford 260/669 UTILIZINGCATALYSTS COMPOSED 0F 3,577,395 5/1971 Lal et a1 252/431 X 3,329,7347/1967 Schleimer et a1. CERTAIN ORGANOMETALLIC 3,542,899 11/1970 Butte260/683.15

COMPLEXES AND TRANSITION METALS OR THEIR COMPOUNDS Joseph H. Merkley,Gastonia, NC.

First National City Bank, New York, N.Y.

Filed: Aug. 31, 1970 Appl. No.: 68,589

Inventor:

Assignee:

References Cited UNITED STATES PATENTS 12/1967 Wofford 260/669 PrimaryExaminer Paul M. Coughlan, Jr. Att0rneyWa1lenstein, Spangenberg, Hattis&

Strampel [57] ABSTRACT Telomerization reactions utilizing catalystsystems composed of (1) liquid hydrocarbon solutions or mixtures ofcomplexes such as those made from (a) nbutylsodium or n-butylpotassium,with (b) alkyllithi ums such as n-butyllithium and (2) transition metalsor their compounds such as Raney nickel and nickel acetylacetonate givea polybutadiene having a high cis-l ,4 content.

27 Claims, No Drawings TELOMERIZATION REACTIONS UTILIZING CATALYSTSCOMPOSED OF CERTAIN ORGANOMETALLIC COMPLEXES AND TRANSITION METALS RTHEIR COMPOUNDS This invention relates to the production of telomersunder certain telomerizing conditions whereby to produce enhancedcontents of microstructures of the cis- 1,4 type. It has been discoveredthat this can be accomplished by carrying out telomerization reactionsin the presence of catalyst systems composed of liquid hydrocarbonsolutions of certain organometallic complexes combined with transitionmetals or compounds thereof.

In copending application, Ser. No. 3,189, filed on Jan. 15, 1970, thereis described the preparation of liquid hydrocarbon solutions ofcomplexes of organolithiums with organometallic compounds in which themetals of said organometallic compounds are one or more taken from thegroup of sodium, potassium, rubidium and cesium. In the above-mentionedapplication, it is also disclosed that these solutions of organometalliccomplexes of Group I metals can be used as catalysts in telomerizationreactions to produce low molecular weight liquid and semi-liquidtelomers from conjugated dienes in good yields. A novel utility of thesecatalysts is disclosed which involves their ability to regulate themicrostructure of the telomers produced during their use intelomerization reactions. For example, it is shown that telomersproduced using only the organolithium constituent of the complex as acatalyst, such as n-butyllithium, possess a high degree of saturatedcyclic structures, as depicted below:

On the other hand, it is there shown that telomers produced using aliquid hydrocarbon solution of a complex containing an. organolithium,such as n-butyllithium, and an organopotassium compound, such asnbutylpotassium, as catalyst, possesses a much higher degree ofunsaturation, coupled with a relatively low viscosity. Unsaturation isessentially exclusively of the vinyl and trans-1,4 types (littlecis-l,4).

It has now been found, in accordance with the pres ent invention, thatthe addition of small amounts of transition metals or their salts to theaforementioned catalyst complexes generally substantially increases theamount of cis-l,4 content of the resultant telomers. A higher cis-l,4content of polybutadienes is known to increase their curing rates andlower their viscosity.

The addition of transition metals or their salts to nbutyllithium orn-butylsodium alone does not cause a comparable increase in cis-l ,4content of the telomers.

The types of transition metals or their salts which can be used in thepractice of this invention vary widely. In general, metals of GroupsVIII b and I b of the Periodic Table can be used','such as nickel,cobalt, iron and copper. Other transition metals which can be usedare'titanium, vanadium, chromium, manganese, zinc and their compounds.Normally, these are employed, in the practice of the invention, in theform of finely divided powders. Activated forms of the metals may beused such as, for example, Raney nickel. In addition, various inorganicand organic salts of the above metals can be employed suc as, forexample, nickelous chloride (NiCl ferric chloride (FeCl cobaltouschloride (CoCl cupric chloride (CuCland the acetylacetonate salts,

H O Other salts oftransition metal series can also be used such asnitrates and sulfates, and metal carbonyls and hydrides can also beused, as well as oxinates, glyoximes and salicylates. It is preferableto remove waters of hydration in these salts, if present, prior to theiruse. These are illustrative examples and are not limitative of thetransition metal salts or compounds. Not all of them are equallyeffective in promoting the formation of cis-l,4 microstructure in thetelomers. Thus, nickel acetylacetonate yields a telomer with 30-35percent cis-l,4 microstructure, while with the much lesshydrocarbon-soluble nickel chloride (NiCl only about 5 percent cis-l ,4microstructure is obtained. Generally, improved results are obtainedwith hydrocarbon-soluble transition metal salts or compounds, andespecially outstanding in this regard are the acetylacetonate salts ofthe transition metals. Generally, it is desirable to utilize thosetransition metals or compounds thereof which produce telomers which havea cis-1,4 content of at least 15 percent and preferably from about 20 toabout 35 percent.

As is disclosed in the aforesaid application Ser. No. 3,189, thecomplexes are particularly advantageously (a) C C alkyllithium compoundsin admixture with (b) C C alkylmetallic compounds in which the metals ofsaid alkylmetallic compounds are one or more from the group of sodium,potassium, rubidium and cesium, especially the n-butylmetalliccompounds. However, in the broader phases of the invention, theorganometallic compounds employed in the production of the compositionsor complexes or the like utilizedin the practice of the presentinvention, in conjunction with the transition metals or compoundsthereof, can comprise C C hydrocarbon organo radicals, said organoradicals being, for instance, cycloalkyl, cycloalkenyl-alkyl, arylalkyl,arylcycloalkyl, cycloalkylaryl, arylcycloalkyl; organo radicals ofheterocyclic character, such as 2- pyridyl and 2-thienyl; ethylenicallyunsaturated organo radicals such as vinyl, allyl and propenyl;polyfunctional organo radicals such as alkylene and polymethythepractice of the invention are variable but, in genwhere R and R are thesame or dissimilar C C hydrocarbon organo radicals; Me is one or moremetals selected from the group of sodium, potassium, rubidium andcesium; x and y are integers reflecting the molar ratios of therespective organometallic compounds comprising the compositions orcomplexes, and

a, h, c and d are integers generally from 1 to 3. lllustrativc examplesof said hydrocarbon organo radicals are n-butyl, sec-butyl, n-amyl,n-dodecyl, cyclopentyl, cyclohexyl, phenyl, tolyl, benzyl, naphthyl, and2,7- dimethylocta-2,6-dien-l,8-yl. The compositions or complexes can beof binary character, as in the case, for example, be n-butyllithium.n-butylpotassium, or even higher. The compositions or complexes can beemployed in the form of solutions thereof in one or more liquidhydrocarbon solvents. Among such solvents are heptane, hexane,cyclohexane, benzene and toluene. These soluble metalorganic complexeswill have compositions in which the organolithium to (other)organoalkali molar ratios will vary considerably depending on the natureof the organo radicals involved. Generally, these ratios will vary fromabout 2:1 to about :1, but may be as high as 100:1 or even l0O0zl.

It is also desirable in certain instances, in the practice of thisinvention, to utilize, in the reaction medium in which the telomers ofthe present invention are produced, Lewis base ethers and aliphatictertiary amines such as diethyl ether, dimethyl ether of ethyleneglycol, tetrahydrofuran, 2-dimethylamino-ethylmethyl ether [(Cl-l -NCl-lCl-l -0-CH and N,N,N',N'- tetramethylethylene diamine [(Cl-l -N-CH --CH-2 a)2l- The complexes are employed, in conjunction with the transitionmetals or the compounds of said transition metals, in the form ofsolution thereof in one or more liquid hydrocarbon solvents except tothe extent that the transition metals or certain of the compounds ofsaid transition metals are not soluble in said solvents in which eventsaid metals or compounds thereof will be in suspension or dispersed insaid solvents. Among such solvents are, by way of illustration, heptane,hexane, octane, isooctane, cyclohexane, methylcyclohexane, benzene,toluene, xylenes, and compatible mixtures of any two or more thereof. Itwill be understood of course, that the different complexes and differenttransition metal compounds will have varying solubilities in differentliquid hydrocarbon solvents. However, in general, the complexes will befound to be soluble to a substantial extent in at least most of saidliquid hydrocarbon solvents to produce clear solutions and preferredtransition metal compounds will likewise be soluble. Where reference ismade to solubility or insolubility of a complex in a given liquidhydrocarbon solvent, the term equivalents" of organometal(s) per literof solution is used to denote concentration. Thus, by way ofillustration, 1 molar equivalent of nbutyllithium dissolved in 1 literof hexane will dissolve 0.1 molar equivalent of n-butylsodium, while1.05 molar equivalents of n-butyllithium dissolved in 1 liter of benzenewill dissolve 0.35 molar equivalents of nbutylsodium. Alkylpotassiumsare generally less readily dissolved.

With regard to the telomerization reactions which are carried out inaccordance with the present invention, the telogens which are used arearomatic compounds, especially aromatic hydrocarbon compounds containingat least one hydrogen capable of being replaced by a lithium atom butdevoid of any other substituents as, for instance, hydroxyl, chlorine,bromine, iodine, carboxyl, and nitro, which substituents arereactivewith the organolithium compositions or complexes which are utilized ascatalysts. Illustrative examples of such telogens are benzene, C C,mono-, diand trialkyl benzenes exemplified by toluene, ethylbcnzene, n-

propylbenzene, isopropylbcnzene, o-, mand pxylenes;1,3,5-trimethyl-benzene; n-, secand tertbutylbenzenes;cyclohexylbenzene; alkyl, notably lllustrative examples of the monomericconjugated diene and vinyl-substituted aromatic compound taxogens, whichmay contain from four to 12 carbon atoms, including those disclosedabove, are isoprene; 1,3- butadiene; 2-methyl-l,3-butadiene; styrene;alphamethylstyrene; l ,4-divinylbenzene; lvinylnaphthalene and2-vinylnaphthalene. Numerous other examples can also be used, many ofwhich are shown, for instance, in US. Pat. No. 3,091,606 which, for thisshowing, is herewith incorporated by reference.

All of the process advantages described in copending application Ser.No. 3,189 accrue to the practice of this invention as well. Thus,molecular weights of the telomers can be controlled readily to produceliquid products of low, medium, or high viscosity by variation of anyone of a number of parameters, such as butadiene or other taxogen feedrate, reaction temperature. telogen concentration, variable lithium topotassium ratio and use of tetramethylethylenediamine (TMEDA) or othersimilar aliphatic tertiary amine cocatalysts.

The complexes and their manner of use, the telogens and taxogens, andall other aspects of the present invention, except in so far as theutilization of the transition metals or the compounds of said transitionmetals is concerned, are disclosed in detail in said application Ser.No. 3,189 the disclosures of which, to the extent that all aspectsthereof have not been reproducedin the present invention, areincorporated herein by reference.

The following examples are illustrative, but in no way limitative, ofthe production of telomers in accordance with the present invention.

EXAMPLE I To 400 ml of toluene was added 0.26g (0.001 moles) of nickelbis-(acetylacetonate), 1.9 g (0.017 moles) of potassium tert-butoxideand 5 ml of TMEDA. To this was added 0.04 moles of n-butyllithium. Themixture was allowed to stir for 5 to 10 minutes to yield the catalystsystem BuLiBuK Ni(0). Butadiene was then added as a gas at a feed rateof 5.1 liters/min. The temperature rose immediately from ambient to 65Cand was maintained at 6570C with external cooling. After 3.25 hours, 3ml of water were added to deactivate the catalyst which was still fullyactive. The toluene was removed under reduced pressure to yield 1,820 glbs/equivalent of catalyst) of a dark colored fluid (viscosity 5.7P at25C) telomeric oil whose molecular weight was 900 (V.P.O.). Themicrostructure of the telomeric polybutadiene oil was found to be 34.3%cis-1,4, 22.7% trans- 1,4 and 43.1% 1,2(vinyl) by both NMR and IRanalysis.

EXAMPLE 2 The procedure of the above Example 1 was carried out using0.15 g (0.001 moles) of cupric chloride (CuCl in place of the nickelacetylacetonate. The yield of telomeric product was 1.3 kg. Themicrostructure of the product was found to be 20.2 percent cisl,4, 23.7%trans-1,4 and 56.1% 1,2(viny1).

EXAMPLE 3 The procedure of Example 1 was followed using as thetransition metal about 0.1 g of finely divided Raney nickel. The yieldof telomeric product-was 1.5 kg. The microstructure of the product wasfound to be 21.4% cis-1,4, 28.2% trans-1,4 and 50.4% 1,2 (vinyl).

EXAMPLE 4 A larger scale preparation of Example 1 was made in which ahigher molecular weight telomer was produced, except that no TMEDA wasadded to this run.

a. To 4.5 liters of toluene was added 19 g of potassium tert-butoxide,2.9 g of nickel-bis-acetylacetonate, and 43 ml of concentrated (90 wtpercent) nbutyllithium. Butadiene gas was fed into the dark red,rapidly-stirred mixture at a rate of 18 liters/min. while maintainingthe reaction temperature at 43-48C. After 6 hours, the viscous reactionmixture was quenched with 2 liters of water and then washed 3 times withwater. After stripping under vacuum to remove toluene, the residualproduct, weighing 24.5 pounds was found to have a molecular weight of2,100 and a viscosity (25C) of 63 Poise. lts microstructure was 31%cis'1,4, 18.5% trans-1,4 and 50.5 percent 1,2 (vinyl).

b. A comparable run to part (a), but produced with no transition metalsalt present, possessed a microstructure with only 3.8% cis-1,4 content(29.9% trans- 1,4 and 66.3% vinyl'or 1,2). lts molecular weight was2,600, and its viscosity at 25C was 66 Poise.

Table 1 shows the microstructure of butadiene telomers wherein differentcatalysts are used, and pointing up sharply the increased content ofcis-1,4 resulting from the utilization of nickel acetylacetonate inconjunction with a (n-BuLi)n-Bul( catalyst.

TABLE 1 MICROSTRUCTURE OF BUTADIENE TELOMERS Catalyst Type Vinyltrans-1,4 cisl ,4 sat'd n-Butyllithium 68.9 7.6 0.0 23.5 (n-BuLihn-BUK50.1 42 l 8.6 (n-BuLi)'n-BuK 49.0 45.5 5.5 1 44.0 45.8 10.2 1

n-BuRb'(n-Bu),Mg 58.4 32.2 9.5 (n-BuLi)'n-BuK 43.1 22.7 34.3 1

0.16 Ni(Acac),

Table 11 shows butadiene telomer microstructures obtained usingdifferent transition metals and salts under the same or similartelomerizing conditions. It will be noted that the use of nickelacetylacetonate, particularly, results in the production ofexceptionally high cis-1,4 contents in the polybutadiene telomers.

TABLE I1 Butadicne Tclomcr Mi'crostructu rc Transition Metal or Salt cis1,4 trans-1,4 vinyl NiCl 4.69 29.87 65.44 CoCl, 16.09 28.05 55.86 FeCl18.07 27.72 54.21 CuCl 20.23 23.66 56.11 Raney Ni 21.38 28.24 50.38Ni(Acac) 31.0 18.5 50.5 Ni(Acac), 31.27 24.97 43.76 Ni(Acac) 34.3 22.743.1 Co(Acac);, 13.78 31.00 55.22 Fe(Acac) 17.90 29.00 53.10 Cu(Acac)-l-l,O 13.37 31.56 55.07

I claim:

1. In a method of preparing telomers in which the telomers are prepared,in the presence of a catalyst, by a reaction between (a) a telogen inthe form of an aromatic compound containing at least one active hydrogencapable of being replaced by a lithium atom but devoid of any othersubstituents which are reactive with the organolithium compound definedhereafter, with (b) at least one taxogen in the form of a conjugateddiene, and wherein there is utilized, as the catalyst, in a hydrogensolvent solution, a complex of at least one organolithium with at leastone organometallic compound in which the metal of said organometalliccompound is selected from the group of sodium, potassium, rubidium andcesium, the organo radicals of said organolithium and saidorganometallic compound being C C hydrocarbon radicals, the improvementwhich comprises carrying out the telomerization reaction in the presenceof at least one member selected from the group consisting of transitionmetals selected from titanium, vanadium, chromium, manganese, zinc,iron, cobalt, nickel, copper and compounds of said metals, saidtransition metals or hydrocarbon-soluble compounds of said metals beingemployed in proportions in the range of about 1 to about 50 mole percentbased on the organometallic complex.

2. The method of claim 1, in which the hydrocarbon solvent is at leastone member of the group of pentane, hexane, heptane, octanes,cyclohexane, cyclooctane, benzene and toluene.

3. The method of claim 1, in which the telogen is toluene and thetaxogen is 1,3-butadiene.

4. The method of claim 2, in which the organolithium is a C -Calkyllithium.

5. The method of claim 1, in which the transition metal compound is atleast one member of the group of the acetylacetonates of cobalt, nickel,copper and iron.

6. The method of claim 4, in which the transition metal compound is atleast one member of the group of the acetylacetonates of cobalt, nickel,copper and iron.

7. The method of claim 4, in which the alkyllithium is n-butyllithium.

8. The method of claim 6, in which the organometallic compound is amember selected from the group of n-butyl-sodium and n-butylpotassium.

9. The method of claim 3, in which the organolithium is n-butyllithium.

10. The method of claim 7, in which the organometallic compound is amember selected from the group of n-butylsodium and n-butylpotassium.

11. The method of claim 6, in which the catalyst complex is an-butyllithiumn-butylpotassium complex.

12. The method of claim 1, in which the organolithium is apolylithioadduct of a conjugated diene selected from the group ofisoprene or l ,B-butadiene, and the organometallic compound is a memberselected from the group of n-butylsodium and n-butylpotassium.

13. The method of claim 1, in which the reaction medium includes a Lewisbase selected from the group of ethers and aliphatic tertiary amines.

'14. In a method of preparing telomers in which the telomers areprepared, in the presence of a catalyst, by a reaction between (a) atelogen in the form of an aromatic compound containing at least oneactive hydrogen capable of being replaced by a lithium atom but devoidof any other substituents which are reactive with the organolithiumcompound defined hereafter, with (b) at least one taxogen in the form ofa conjugated diene monomer, and wherein there is utilized, as thecatalyst, a complex of at least one organolithium with at least oneorganometallic compound in which the metal of said organometalliccompound is selected from the group of sodium, potassium, rubidium andcesium, the organo radicals of said organolithium and saidorganometallic compound being C C hydrocarbon radicals, the improvementwhich comprises carrying out the t'elomerization reaction in thepresence of at least one member selected from the group consisting oftransition metals selected from tita- I nium, vanadium, chromium,manganese, zinc, iron, cobalt, nickel, copper, and compounds of saidmetals, said transition metals 'or hydrocarbon-soluble compounds of saidmetals being employed in proportions in the range of about to about molepercent based on the organometallic complex.

15. The method of claim 14, in which the telogen is toluene and thetaxogen is 1,3-butadiene.

16. The method of claim 14, in which the reaction medium includes aLewis base selected from the group of ethers and aliphatic tertiaryamines.

17. The method of claim 15, in which the reaction medium includestetramethyl ethylenediamine.

18. The method of claim 14, in whichthe transition metal compound is atleast one member of the group of acetylacetonates of cobalt, nickel,copper and iron.

19. The method of claim 16, in which the transition metal compound isnickel acetylacetonate.

20. In a method of preparing telomers which comprises providing.(a) atelogen in the form of an aromatic compound containing at least oneactive hydrogen capable of being replaced by a lithium atom but devoidof any other substituents which are reactive with the organolithiumcompound defined hereafter, (b) a complex of at least one organolithiumwith at least one organometallic compound in which the metal of saidorganometallic compound is selected from the group of sodium, potassium,rubidium and cesium, the organo radicals of said organolithium and saidorganometallic compound being C -C hydrocarbon radicals. said complexbeing in solution in a hydrocarbon, and (c) at least one member selectedfrom-the group consisting of transition metals selected from titanium,vanadium, chromium, manganese, zinc, iron, cobalt, nickel, copper andcompounds of said metals, said transition metals or compounds of saidmetals being employed in proportions in the range of about 1 to about 50mole percent based on the organometallic complex, and then graduallyadding to reaction mixture at least one taxogen in the form of aconjugated diene monomer.

21. The method of claim 20, in which the telogen is toluene and thetaxogen is l,3-butadiene.

22. The method of claim 21, in which the organolithium is a C -Calkyllithium.

23. The method of claim 22, in which the transition metal compound isnickel acetylacetonate.

24. The method of claim 23, in which the organome-' tallic compound is amember selected from the group of n-butylsodium and n-butylpotassium.

25. In a method of preparing telomers which comprises providing areaction mixture containing (a) a telogen in the form of an aromaticcompound containing at least one active hydrogen capable of beingreplaced by a lithium atom but devoid of any other substituents whichare reactive with the organolithium compound defined hereafter, (b) acomplex of at least one organolithium with at least one organometalliccompound in which the metal of said organometallic compound is selectedfrom the group of sodium, potassium, rubidium and cesium, the organoradicals of said organolithium and said organometallic compound being C-C hydrocarbon radicals, and (c) at least one member selected from thegroup consisting of transition metals selected from titanium, vanadium,chromium, manganese, zinc, iron, cobalt, nickel, copper and compounds ofsaid metals, said transition metals or hydrocarbon-soluble compounds ofsaid metals being employed in proportions in the range of about 1 toabout 50 mole percent based on the organometallic complex, and thengradually adding to reaction mixture at least one taxogen in the form ofa conjugated diene monomer.

26. The method of claim 25, in which the telogen is toluene and thetaxogen is 1,3-butadiene.

27. The method of claim 26, in which the transition metal compound isnickel acetylacetonate.

2. The method of claim 1, in which the hydrocarbon solvent is at leastone member of the group of pentane, hexane, heptane, octanes,cyclohexane, cyclooctane, benzene and toluene.
 3. The method of claim 1,in which the telogen is toluene and the taxogen is 1,3-butadiene.
 4. Themethod of claim 2, in which the organolithium is a C3-C6 alkyllithium.5. The method of claim 1, in which the transition metal compound is atleast one member of the group of the acetylacetonates of cobalt, nickel,copper and iron.
 6. The method of claim 4, in which the transition metalcompound is at least one member of the group of the acetylacetonates ofcobalt, nickel, copper and iron.
 7. The method of claim 4, in which thealkyllithium is n-butyllithium.
 8. The method of claim 6, in which theorganometallic compound is a member selected from the group ofn-butyl-sodium and n-butylpotassium.
 9. The method of claim 3, in whichthe organolithium is n-butyllithium.
 10. The method of claim 7, in whichthe organometallic compound is a member selected from the group ofn-butylsodium and n-butylpotassium.
 11. The method of claim 6, in whichthe catalyst complex is a n-butyllithium.n-butylpotassium complex. 12.The method of claim 1, in which the organolithium is a polylithioadductof a conjugated diene selected from the group of isoprene or1,3-butadiene, and the organometallic compound is a member selected fromthe group of n-butylsodium and n-butylpotassium.
 13. The method of claim1, in which the reaction medium includes a Lewis base selected from thegroup of ethers and aliphatic tertiary amines.
 14. In a method ofpreparing telomers in which the telomers are prepared, in the presenceof a catalyst, by a reaction between (a) a telogen in the form of anaromatic compound containing at least one active hydrogen capable ofbeing replaced by a lithium atom but devoid of any other substituentswhich are reactive with the organolithium compound defined hereafter,with (b) at least one taxogen in the form of a conjugated diene monomer,and wherein there is utilized, as the catalyst, a complex of at leastone organolithium with at least one organometallic compound in which themetal of said organometallic compound is selected from the group ofsodium, potassium, rubidium and cesium, the organo radicals of saidorganolithium and said organometallic compound being C2-C18 hydrocarbonradicals, the improvement which comprises carrying out thetelomerization reaction in the presence of at least one member selectedfrom the group consisting of transition metals selected from titanium,vanadium, chromium, manganese, zinc, iron, cobalt, nickel, copper, andcompounds of said metals, said transition metals or hydrocarbon-solublecompounds of said metals being employed in proportions in the range ofabout 5 to about 20 mole percent based on The organometallic complex.15. The method of claim 14, in which the telogen is toluene and thetaxogen is 1,3-butadiene.
 16. The method of claim 14, in which thereaction medium includes a Lewis base selected from the group of ethersand aliphatic tertiary amines.
 17. The method of claim 15, in which thereaction medium includes tetramethyl ethylenediamine.
 18. The method ofclaim 14, in which the transition metal compound is at least one memberof the group of acetylacetonates of cobalt, nickel, copper and iron. 19.The method of claim 16, in which the transition metal compound is nickelacetylacetonate.
 20. In a method of preparing telomers which comprisesproviding (a) a telogen in the form of an aromatic compound containingat least one active hydrogen capable of being replaced by a lithium atombut devoid of any other substituents which are reactive with theorganolithium compound defined hereafter, (b) a complex of at least oneorganolithium with at least one organometallic compound in which themetal of said organometallic compound is selected from the group ofsodium, potassium, rubidium and cesium, the organo radicals of saidorganolithium and said organometallic compound being C2-C18 hydrocarbonradicals, said complex being in solution in a hydrocarbon, and (c) atleast one member selected from the group consisting of transition metalsselected from titanium, vanadium, chromium, manganese, zinc, iron,cobalt, nickel, copper and compounds of said metals, said transitionmetals or compounds of said metals being employed in proportions in therange of about 1 to about 50 mole percent based on the organometalliccomplex, and then gradually adding to reaction mixture at least onetaxogen in the form of a conjugated diene monomer.
 21. The method ofclaim 20, in which the telogen is toluene and the taxogen is1,3-butadiene.
 22. The method of claim 21, in which the organolithium isa C3-C6 alkyllithium.
 23. The method of claim 22, in which thetransition metal compound is nickel acetylacetonate.
 24. The method ofclaim 23, in which the organometallic compound is a member selected fromthe group of n-butylsodium and n-butylpotassium.
 25. In a method ofpreparing telomers which comprises providing a reaction mixturecontaining (a) a telogen in the form of an aromatic compound containingat least one active hydrogen capable of being replaced by a lithium atombut devoid of any other substituents which are reactive with theorganolithium compound defined hereafter, (b) a complex of at least oneorganolithium with at least one organometallic compound in which themetal of said organometallic compound is selected from the group ofsodium, potassium, rubidium and cesium, the organo radicals of saidorganolithium and said organometallic compound being C2-C18 hydrocarbonradicals, and (c) at least one member selected from the group consistingof transition metals selected from titanium, vanadium, chromium,manganese, zinc, iron, cobalt, nickel, copper and compounds of saidmetals, said transition metals or hydrocarbon-soluble compounds of saidmetals being employed in proportions in the range of about 1 to about 50mole percent based on the organometallic complex, and then graduallyadding to reaction mixture at least one taxogen in the form of aconjugated diene monomer.
 26. The method of claim 25, in which thetelogen is toluene and the taxogen is 1,3-butadiene.
 27. The method ofclaim 26, in which the transition metal compound is nickelacetylacetonate.